Clinical relevance of mutations and gene-expression changes in adult acute myeloid leukemia with normal cytogenetics: are we ready for a prognostically prioritized molecular classification?

Allogeneic hematopoietic cell transplantation for acute myeloid leukemia during first complete remission: a clinical perspective

Allogeneic hematopoietic cell transplantation (HCT) is the most potent therapy for preventing relapse of acute myeloid leukemia (AML). Although its efficacy is compromised by a high risk of treatment-related morbidity and mortality, an accumulating body of evidence has led to the general recommendation favoring allogeneic HCT from a matched sibling donor during first complete remission (CR1) for younger patients with cytogenetically intermediate- or high-risk AML. Over the past few decades, this field has seen a great many advancements. The indications for allogeneic HCT have been refined by taking into account the molecular profiles of leukemic cells and the degree of comorbidities. The introduction of high-resolution human leukocyte antigen-typing technology and advances in immunosuppressive therapy and supportive care measures have improved outcomes in alternative donor transplantation, while the parallel growth of unrelated donor registries and greater use of umbilical cord blood and haploidentical donors have considerably improved the chance of finding an alternative donor. The development of reduced-intensity and non-myeloablative conditioning has made it possible to receive allogeneic HCT for patients who might once have been considered ineligible due to advanced age or comorbidities. Thanks to these advances, the role of allogeneic HCT during CR1 has become progressively more important in the treatment of AML.

Prognostic implication of gene mutations on overall survival in the adult acute myeloid leukemia patients receiving or not receiving allogeneic hematopoietic stem cell transplantations

Several gene mutations have been shown to provide clinical implications in patients with acute myeloid leukemia (AML). However, the prognostic impact of gene mutations in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains unclear. We retrospectively evaluated the clinical implications of 8 gene mutations in 325 adult AML patients; 100 of them received allo-HSCT and 225 did not. The genetic alterations analyzed included NPM1, FLT3-ITD, FLT3-TKD, CEBPA, RUNX1, RAS, MLL-PTD, and WT1. In patients who did not receive allo-HSCT, older age, higher WBC count, higher lactate dehydrogenase level, unfavorable karyotype, and RUNX1 mutation were significantly associated with poor overall survival (OS), while CEBPA double mutation (CEBPA(double-mut)) and NPM1(mut)/FLT3-ITD(neg) were associated with good outcome. However, in patients who received allo-HSCT, only refractory disease status at the time of HSCT and unfavorable karyotype were independent poor prognostic factors. Surprisingly, RUNX1 mutation was an independent good prognostic factor for OS in multivariate analysis. The prognostic impact of FLT3-ITD or NPM1(mut)/FLT3-ITD(neg) was lost in this group of patients receiving allo-HSCT, while CEBPA(double-mut) showed a trend to be a good prognostic factor. In conclusion, allo-HSCT can ameliorate the unfavorable influence of some poor-risk gene mutations in AML patients. Unexpectedly, the RUNX1 mutation showed a favorable prognostic impact in the context of allo-HSCT. These results need to be confirmed by further studies with more AML patients.

Impact of ABCB1 single nucleotide polymorphisms 1236C>T and 2677G>T on overall survival in FLT3 wild-type de novo AML patients with normal karyotype

Drug resistance is a clinically relevant problem in the treatment of acute myeloid leukaemia (AML). We have previously reported a relationship between single nucleotide polymorphisms (SNPs) of ABCB1, encoding the multi-drug transporter P-glycoprotein, and overall survival (OS) in normal karyotype (NK)-AML. Here we extended this material, enabling subgroup analysis based on FLT3 and NPM1 status, to further elucidate the influence of ABCB1 SNPs. De novo NK-AML patients (n = 201) were analysed for 1199G>A, 1236C>T, 2677G>T/A and 3435C>T, and correlations to outcome were investigated. FLT3 wild-type 1236C/C patients have significantly shorter OS compared to patients carrying the variant allele; medians 20 vs. 49 months, respectively, P = 0·017. There was also an inferior outcome in FLT3 wild-type 2677G/G patients compared to patients carrying the variant allele, median OS 20 vs. 35 months, respectively, P = 0·039. This was confirmed in Cox regression analysis. Our results indicate that ABCB1 1236C>T and 2677G>T may be used as prognostic markers to distinguish relatively high risk patients in the intermediate risk FLT3 wild-type group, which may contribute to future individualizing of treatment strategies.

AML genomics for the clinician

Acute myeloid leukemia (AML) is a heterogeneous disease, characterized by frequent resistance to available chemotherapeutic agents. The basic therapy for patients with AML has changed little over the past 30 years. Improvements in outcome in recent decades in younger adult cohorts have generally been ascribed to better supportive care (ie, transfusion and antimicrobial therapy); older adults with AML continue to fare poorly. The explosion of new knowledge regarding the AML genome has yet to be translated into therapeutic benefit, but analysis of specific molecular features in AML samples has enabled the field to more accurately parse out prognosis and assign appropriate therapies (eg, chemotherapy vs allogeneic stem cell transplantation) for groups of patients. Cytogenetic analysis, whether by metaphase or interphase analysis, has been the main tool used to divide patients into varying prognostic subsets, but it has been modified in recent years to include assessment of mutations in a small number of genes. In the past several years, new technologies have provided strategies to interrogate individual cancer genomes in a broad and in-depth fashion. The present article discusses the potential of these new technologies, particularly gene panel and whole-exome or whole-genome sequencing, to improve diagnosis, prognosis, and therapeutic outcome in AML.

Persistence of DNMT3A mutations at long-term remission in adult patients with AML

Mutations in DNMT3A, the gene encoding DNA methyltransferase 3 alpha, have been identified as molecular drivers in acute myeloid leukaemia (AML) with possible implications for minimal residual disease monitoring and prognosis. To further explore the utility of DNMT3A mutations as biomarkers for AML, we developed assays for sensitive detection of recurrent mutations affecting residue R882. Analysis of DNA from 298 diagnostic AML samples revealed DNMT3A mutations in 45 cases (15%), which coincided with mutations in NPM1, FLT3 and IDH1. DNMT3A mutations were stable in 12 of 13 patients presenting with relapse or secondary myelodysplastic syndrome, but were also present in remission samples from 14 patients (at allele frequencies of <1-50%) up to 8 years after initial AML diagnosis, despite the loss of all other molecular AML markers. The mutant DNMT3A allele burden was not related to the clinical course of disease. Cell sorting demonstrated the presence of DNMT3A mutations in leukaemic blasts, but also at lower allele frequencies in T and B-cells from the same patients. Our data are consistent with the recent finding of preleukaemic stem cells in AML, which are resistant to chemotherapy. The persistence of DNMT3A mutations during remission may have important implications for the management of AML.

ASXL1 and DNMT3A mutation in a cytogenetically normal B3 thymoma

The molecular drivers of thymoma are poorly understood. Outside of the identification of rarely occurring epidermal growth factor receptor and v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog mutations via candidate gene sequencing, mutations in common cancer genes have yet to be observed. Only a single thymoma genome sequence has been previously reported, with no mutations in known cancer genes identified. Thus, we attempted to identify somatic driver mutations in a cytogenetically normal thymoma. A stage IVB type B3 thymoma from a 47-year-old male of Asian descent with no history of myasthenia gravis or other autoimmune condition was genomically evaluated. Exome sequencing and low-pass whole-genome sequencing was performed to identify somatic point mutations, copy number changes and structural variants. Mutations in known tumor suppressors DNMT3A (p.G728D) and ASXL1 (p.E657fs), consistent with mutations of known consequence in acute myeloid leukemia, were identified. Contrary to a previous report, this finding suggests the genetic etiology of thymomas may not be fundamentally distinct from other tumor types. Rather, these findings suggest that further sequencing of cytogenetically normal thymoma samples should reveal the specific molecular drivers of thymoma.

MicroRNA-26a-5p and microRNA-23b-3p up-regulate peroxiredoxin III in acute myeloid leukemia

MicroRNAs (miRNAs) are small RNAs that regulate target gene expression. Using microarray-based miRNA expression profiling, we compared the miRNA expression in granulocytes from four patients with acute myeloid leukemia and four healthy controls. Thirty-four miRNAs were found to be differentially expressed, including 20 miRNAs that were up-regulated and 14 miRNAs that were down-regulated. The expression of selected miRNAs (miR-26a-5p and miR-23b-3p) was independently validated in 20 patients and 12 healthy controls. Notably, we demonstrated that peroxiredoxin III (PrxIII) is a common direct target of both miR-26a-5p and miR-23b-3p. Furthermore, these results indicate that the two decreased miRNAs could scavenge cellular reactive oxygen species (ROS) by targeting the PrxIII gene. These findings are discussed with regard to the known function of PrxIII as a ROS scavenger and the high endogenous ROS levels required for hematopoietic stem cell differentiation. These findings may potentially offer insights into the pathological relationships between miR-26a-5p, miR-23b-3p and leukemogenesis.

The role of miR-29 family members in malignant hematopoiesis

AIMS

MicroRNAs of the miR-29 family members were one of the first microRNAs identified as possible therapeutic agents in malignant hematopoiesis. The aim of our review is to summarize the current state of knowledge on miR-29 family members.

METHODS

We performed literature searches involving miR-29 family members and their relationship to individual hematological malignancies, namely acute myeloid leukemia (AML), chronic lymphoblastic leukemia (CLL) and chronic myeloid leukemia (CML). We also searched for subgroups of hematological malignancies, e.g. multiple myeloma, that are regarded as members of the acute or chronic types of leukemias.

RESULTS

A number of genes appear to be regulated by miR-29 family members in various physiological and pathological situations. In our view regulation of Tcl-1, Mcl-1 and DNA methyltransferases is relevant in case of hematological malignancies, hence these are the focus of this review. miR-29 family members also function during normal T-cell and B-cell development.

CONCLUSION

MiR-29 family members appear to govern some general features in commonly heterogenous hematological malignancies and therefore form a potential target for treatment.

Genomic characterization of acute leukemias

Over the past two decades, hematologic malignancies have been extensively evaluated due to the introduction of powerful technologies, such as conventional karyotyping, FISH analysis, gene and microRNA expression profiling, array comparative genomic hybridization and SNP arrays, and next-generation sequencing (including whole-exome sequencing and RNA-seq). These analyses have allowed for the refinement of the mechanisms underlying the leukemic transformation in several oncohematologic disorders and, more importantly, they have permitted the definition of novel prognostic algorithms aimed at stratifying patients at the onset of disease and, consequently, treating them in the most appropriate manner. Furthermore, the identification of specific molecular markers is opening the door to targeted and personalized medicine. The most important findings on novel acquisitions in the context of acute lymphoblastic leukemia of both B and T lineage and de novo acute myeloid leukemia are described in this review.

TET2 gene mutation is unfavorable prognostic factor in cytogenetically normal acute myeloid leukemia patients with NPM1+ and FLT3-ITD - mutations

Cytogenetically normal acute myeloid leukemia (cn-AML) is a group of heterogeneous diseases. Gene mutations are increasingly used to assess the prognosis of cn-AML patients and guide risk-adapted treatment. In the present study, we analyzed the molecular genetics characteristics of 373 adult cn-AML patients and explored the relationship between TET2 gene mutations or different genetic mutation patterns and prognosis. We found that 16.1 % of patients had TET2 mutations, 31.6 % had FLT3 internal tandem duplications (ITDs), 6.2 % had FLT3 tyrosine kinase domain mutations, 2.4 % had c-KIT mutations, 37.8 % had NPM1 mutations, 11.3 % had WT1 mutations, 5.9 % had RUNX1 mutations, 11.5 % had ASXL1 mutations, 3.8 % had MLL-PTDs, 7.8 % had IDH1 mutations, 7.8 % had NRAS mutations, 12.3 % had IDH2 mutations, 1.6 % had EZH2 mutations, and 14.7 % had DNMT3A mutations, while none had CBL mutations. Gene mutations were detected in 76.94 % (287/373) of all patients. In the NPM1m(+) patients, those with TET2 mutations were associated with a shorter median overall survival (OS) as compared to TET2 wild-type (wt) patients (9.9 vs. 27.0 months, respectively; P = 0.023); Interestingly, the TET2 mutation was identified as an unfavorable prognostic factor and was closely associated with a shorter median OS as compared to TET2-wt (9.5 vs. 32.2 months, respectively; P = 0.013) in the NPM1m(+)/FLT3-ITDm(-) patient group. Thus, identification of TET2 combined with classic NPM1 and FLT3-ITD mutations allowed us to stratify cn-AML into distinct subtypes.

The Prognostic Relevance of BAALC and ERG Expression Levels in Cytogenetically Normal Pediatric Acute Myeloid Leukemia

Cytogenetic aberrations are important prognostic factors in acute myeloid leukemia (AML). About 45 % of de novo adult AML and 20 % of pediatric AML lack cytogenetic abnormalities, so identification of predictive molecular markers might improve therapy. Mutation status of FLT3, NPM1 genes and gene expression levels of ERG, BAALC have been postulated as possible prognostic markers in pediatric AML with normal karyotype. Pretreatment blood samples from 47 cytogenetically normal AML patients were analysed for BAALC and ERG expression using real time RT-PCR. The patients were dichotomized at BAALC and ERG mean expression into low and high expression based on the median expression as cutoff. BAALC showed high expression in (24/47; 51.1 %) of patients and ERG high expression was detected in (22/47; 46.6 %). With follow-up for 1 year, patients with high BAALC and high ERG had inferior EFS (P = 0.001, P = 0.017 respectively), overall survival (P = 0.001, 0.08 respectively), and low rates of induction remission (P = 0.001, P = 0.0017 respectively) as compared to those with low expression. Also there was significant positive association between high expression of BAALC; ERG and FLT-ITD mutations (P = 0.016; P = 0.007 respectively). Multivariable analysis confirmed that high BAALC expression is an independent risk factor for EFS [HR for EFS 1.9(1.04-3.46) P = 0.037]; and OS [HR OS 1.55(1.7-3.36) P = 0.03].

IN CONCLUSION

Over expression of BAALC could predict adverse clinical outcome and may define important risk factor in cytogenetically normal pediatric AML.

Allogeneic hematopoietic cell transplant for acute myeloid leukemia: Current state in 2013 and future directions

Acute myeloid leukemia (AML) represents a heterogeneous group of high-grade myeloid neoplasms of the elderly with variable outcomes. Though remission-induction is an important first step in the management of AML, additional treatment strategies are essential to ensure long-term disease-free survival. Recent pivotal advances in understanding the genetics and molecular biology of AML have allowed for a risk-adapted approach in its management based on relapse-risk. Allogeneic hematopoietic cell transplantation (allo-HCT) represents an effective therapeutic strategy in AML providing the possibility of cure with potent graft-versus-leukemia reactions, with a demonstrable survival advantage in younger patients with intermediate- or poor-risk cytogenetics. Herein we review the published data regarding the role of allo-HCT in adults with AML. We searched MEDLINE/PubMed and EMBASE/Ovid. In addition, we searched reference lists of relevant articles, conference proceedings and ongoing trial databases. We discuss the role of allo-HCT in AML patients stratified by cytogenetic- and molecular-risk in first complete remission, as well as allo-HCT as an option in relapsed/refractory AML. Besides the conventional sibling and unrelated donor allografts, we review the available data and recent advances for alternative donor sources such as haploidentical grafts and umbilical cord blood. We also discuss conditioning regimens, including reduced intensity conditioning which has broadened the applicability of allo-HCT. Finally we explore recent advances and future possibilities and directions of allo-HCT in AML. Practical therapeutic recommendations have been made where possible based on available data and expert opinion.

Intronic miR-3151 within BAALC drives leukemogenesis by deregulating the TP53 pathway

The BAALC/miR-3151 locus on chromosome 8q22 contains both the BAALC gene (for brain and acute leukemia, cytoplasmic) and miR-3151, which is located in intron 1 of BAALC. Older acute myeloid leukemia (AML) patients with high expression of both miR-3151 and the BAALC mRNA transcript have a low survival prognosis, and miR-3151 and BAALC expression is associated with poor survival independently of each other. We found that miR-3151 functioned as the oncogenic driver of the BAALC/miR-3151 locus. Increased production of miR-3151 reduced the apoptosis and chemosensitivity of AML cell lines and increased leukemogenesis in mice. Disruption of the TP53-mediated apoptosis pathway occurred in leukemia cells overexpressing miR-3151 and the miR-3151 bound to the 3' untranslated region of TP53. In contrast, BAALC alone had only limited oncogenic activity. We found that miR-3151 contains its own regulatory element, thus partly uncoupling miR-3151 expression from that of the BAALC transcript. Both genes were bound and stimulated by a complex of the transcription factors SP1 and nuclear factor κB (SP1/NF-κB). Disruption of SP1/NF-κB binding reduced both miR-3151 and BAALC expression. However, expression of only BAALC, but not miR-3151, was stimulated by the transcription factor RUNX1, suggesting a mechanism for the partly discordant expression of miR-3151 and BAALC observed in AML patients. Similar to the AML cells, in melanoma cell lines, overexpression of miR-3151 reduced the abundance of TP53, and knockdown of miR-3151 increased caspase activity, whereas miR-3151 overexpression reduced caspase activity. Thus, this oncogenic miR-3151 may also have a role in solid tumors.

Association of nitric oxide synthase 3 (NOS3) 894 G>T polymorphism with prognostic outcomes of anthracycline in Chinese patients with acute myeloid leukaemia

The aim of the present study was to investigate the influence of the nitric oxide synthase 3 (NOS3) 894 G>T polymorphism on prognostic outcomes of anthracycline in Chinese patients with de novo intermediate-risk acute myeloid leukaemia (AML) and to examine the gene expression level in relation to genetic variation. In all, 225 Chinese patients with intermediate-risk AML (at the complete remission stage) treated with anthracycline were enrolled in the study. The 894 G>T polymorphism of the NOS3 gene was analysed by allele-specific matrix-assisted laser desorption ionization time-of-flight. Expression of NOS3 mRNA was tested in 72 patients of known genotype for NOS3 894 G>T. The clinical characteristics of these patients were obtained from medical records. Survival analysis showed that patients with AML (GG genotype) had a longer overall survival (OS; P = 0.006). After adjusting for age, gender, leucocyte count, haemoglobin level, platelet level, French, American and Britain (FAB) classification, lactate dehydrogenase levels, Eastern Cooperative Oncology Group Performance Status, nucleophosmin gene and fms-related tyrosine kinase 3 gene, multivariate survival analysis showed that the NOS3 894 G>T polymorphism appeared to be a predicting factor for OS (P = 0.014; hazard ratio = 1.856). However, no significant associations between the NOS3 894 G>T polymorphism and relapse-free survival and relapse in patients with AML were observed. Gene expression levels were significantly higher in patients with the GG genotype than in patients with the GT and TT genotypes (P = 0.033). The findings suggest that the NOS3 894 G>T variant may be a biomarker for the prediction of OS in Chinese patients with AML.

Competing views on cancer

Despite intense research efforts that have provided enormous insight, cancer continues to be a poorly understood disease. There has been much debate over whether the cancerous state can be said to originate in a single cell or whether it is a reflection of aberrant behaviour on the part of a 'society of cells'. This article presents, in the form of a debate conducted among the authors, three views of how the problem might be addressed. We do not claim that the views exhaust all possibilities. These views are (a) the tissue organization field theory (TOFT) that is based on a breakdown of tissue organization involving many cells from different embryological layers, (b) the cancer stem cell (CSC) hypothesis that focuses on genetic and epigenetic changes that take place within single cells, and (c) the proposition that rewiring of the cell's protein interaction networks mediated by intrinsically disordered proteins (IDPs) drives the tumorigenic process. The views are based on different philosophical approaches. In detail, they differ on some points and agree on others. It is left to the reader to decide whether one approach to understanding cancer appears more promising than the other.

Prognostic significance of Tet methylcytosine dioxygenase 2 (TET2) gene mutations in adult patients with acute myeloid leukemia: a meta-analysis

Tet methylcytosine dioxygenase 2 (TET2) gene mutations have recently been recognized in acute myeloid leukemia (AML). We performed a meta-analysis to evaluate the controversial prognostic significance of TET2 mutations in AML. Eight studies, covering 2552 patients with AML, were included in this analysis. Pooled hazard ratios (HRs) indicated that TET2 mutations had a poor prognostic impact on the survival of patients with AML. The combined HR for overall survival (OS) was 1.53 and the summary HR for event-free survival (EFS) was 1.64. Additionally, TET2 mutations appeared to be an adverse prognostic indicator in both patients with cytogenetically normal (CN)-AML (HR for OS: 1.43 and HR for EFS: 1.76) and subgroups of patients with favorable-risk genotypes (HR for EFS: 2.35) and intermediate-I-risk genotypes (HR for EFS: 1.57). These findings indicate that TET2 mutations have an adverse impact on prognosis and may help to justify risk-adapted therapeutic strategies for patients with AML.

Overexpression of Wilms tumor 1 gene as a negative prognostic indicator in acute myeloid leukemia

Chromosomal aberrations are useful in assessing treatment options and clinical outcomes of acute myeloid leukemia (AML) patients. However, 40 ∼ 50% of the AML patients showed no chromosomal abnormalities, i.e., with normal cytogenetics aka the CN-AML patients. Testing of molecular aberrations such as FLT3 or NPM1 can help to define clinical outcomes in the CN-AML patients but with various successes. Goal of this study was to test the possibility of Wilms' tumor 1 (WT1) gene overexpression as an additional molecular biomarker. A total of 103 CN-AML patients, among which 28% had overexpressed WT1, were studied over a period of 38 months. Patient's response to induction chemotherapy as measured by the complete remission (CR) rate, disease-free survival (DFS) and overall survival (OS) were measured. Our data suggested that WT1 overexpression correlated negatively with the CR rate, DFS and OS. Consistent with previous reports, CN-AML patients can be divided into three different risk subgroups based on the status of known molecular abnormalities, i.e., the favorable (NPM1(mt)/no FLT3(ITD)), the unfavorable (FLT3(ITD)) and the intermediate risk subgroups. The WT1 overexpression significantly reduced the CR, DFS and OS in both the favorable and unfavorable groups. As the results, patients with normal WT1 gene expression in the favorable risk group showed the best clinical outcomes and all survived with complete remission and disease-free survival over the 37 month study period; in contrast, patients with WT1 overexpression in the unfavorable risk group displayed the worst clinical outcomes. WT1 overexpression by itself is an independent and negative indicator for predicting CR rate, DFS and OS of the CN-AML patients; moreover, it increases the statistical power of predicting the same clinical outcomes when it is combined with the NPM1(mt) or the FLT3(ITD) genotypes that are the good or poor prognostic markers of CN-AML.

Recent advances and novel agents for FLT3 mutated acute myeloid leukemia

Acute myeloid leukemia (AML) is a devastating hematologic malignancy that affects both older adults as well as children. Treatments available for AML largely depend on cytotoxic agents and often the only curative option is an allogeneic bone marrow transplant, an option limited to young persons and associated with high morbidity and mortality. There is an urgent need for the identification of new myeloid targets and an understanding of the key genetic mutations involved in disease progression and prognosis. One such mutation is the internal tandem duplication (ITD) in the FMS-like tyrosine kinase receptor-3 (FLT3) gene which confers an inferior outcome that is attributed to a higher relapse rate. In this review, we evaluate the FLT3-ITD mutation and discuss the recent data regarding emerging approaches using FLT3 inhibitors for the treatment of AML.

Role of genotype-based approach in the clinical management of adult acute myeloid leukemia with normal cytogenetics

Acute myeloid leukemia (AML) is the most common form of acute leukemia affecting adults. Although it is a complex disease driven by numerous genetic and epigenetic abnormalities, nearly 50% of patients exhibit a normal karyotype (CN-AML) with an intermediate cytogenetic risk. However, a widespread genomic analysis has recently shown the recurrence of genomic aberrations in this category (mutations of FLT3, CEBPA, NPM1, RUNX1, TET2, IDH1/2, DNMT3A, ASXL1, MLL and WT1) thus revealing its marked genomic heterogeneity. In this perspective, a global gene expression analysis of AML patients provides an independent prognostic marker to categorize each patient into clinic-pathologic subgroups based on its molecular genetic defects. Consistently such classification, taking into account the uniqueness of each AML patient, furnishes an individualized treatment approach leading a step closer to personalized medicine. Overall the genome-wide analysis of AML patients, by providing novel insights into biology of this tumor, furnishes accurate prognostic markers as well as useful tools for selecting the most appropriate treatment option. Moreover it provides novel therapeutic targets useful to enhance efficacy of the current anti-AML therapeutics. Here we describe the prognostic relevance of such new genetic data and discuss how this approach can be used to improve survival and treatment of AML patients.

Treatment of de novo acute myeloid leukemia in the United States: a report from the Patterns of Care program

Few US studies have examined patterns of care (POC) for acute myeloid leukemia (AML) in community settings. We examined treatment and survival in 978 adults with AML sampled from Surveillance, Epidemiology, and End Results (SEER) registries through the POC program. Logistic regression was used to evaluate the association between patient/hospital characteristics and receipt of chemotherapy and allogeneic transplant. Survival was examined using proportional hazards models. Treatment with cytarabine/anthracycline occurred in > 80% of patients without acute promeyelocytic leukemia (non-APL) < 60, but only about one-third of older non-APL patients. Ultimately, 27% of those < 60 received an allogeneic transplant. Thirty-seven percent of those < 40 and 4% of those ≥ 80 were alive at the end of follow-up. About three-quarters of patients with APL received all-trans retinoic acid (ATRA) and either an anthracycline or arsenic trioxide, with 71% surviving. Age and APL diagnosis were the strongest predictors of treatment and survival. Trends in dissemination of novel diagnostic tests and treatments and in survival will be monitored by POC in future years.

Implications of the miR-10 family in chemotherapy response of NPM1-mutated AML

Nucleophosmin-mutated acute myeloid leukemia (NPM1mut-AML) patients have a high rate of complete remission (CR) to induction chemotherapy. However, the mechanisms responsible for such effects are unknown. Because miR-10 family members are expressed at high levels in NPM1mut-AML, we evaluated whether these microRNAs could predict chemotherapy response in AML. We found that high baseline miR-10 family expression in 54 untreated cytogenetically heterogeneous AML patients was associated with achieving CR. However, when we included NPM1 mutation status in the multivariable model, there was a significant interaction effect between miR-10a-5p expression and NPM1 mutation status. Similar results were observed when using a second cohort of 183 cytogenetically normal older (age ≥ 60 years) AML patients. Loss- and gain-of-function experiments using miR-10a-5p in cell lines and primary blasts did not demonstrate any effect in apoptosis or cell proliferation at baseline or after chemotherapy. These data support a bystander role for the miR-10 family in NPM1mut-AML.

Decreased survival in normal karyotype AML with single-nucleotide polymorphisms in genes encoding the AraC metabolizing enzymes cytidine deaminase and 5'-nucleotidase

De novo acute myeloid leukemia with normal karyotype (NK-AML) comprises a large group of patients with no common cytogenetic alterations and with a large variation in treatment response. Single-nucleotide polymorphisms (SNPs) in genes related to the metabolism of the nucleoside analogue AraC, the backbone in AML treatment, might affect drug sensitivity and treatment outcome. Therefore, SNPs may serve as prognostic biomarkers aiding clinicians in individualized treatment decisions, with the aim of improving patient outcomes. We analyzed polymorphisms in genes encoding cytidine deaminase (CDA 79A>C rs2072671 and -451C>T rs532545), 5'-nucleotidase (cN-II 7A>G rs10883841), and deoxycytidine kinase (DCK 3'UTR 948T>C rs4643786) in 205 de novo NK-AML patients. In FLT3-internal tandem duplication (ITD)-positive patients, the CDA 79C/C and -451T/T genotypes were associated with shorter overall survival compared to other genotypes (5 vs. 24 months, P < 0.001 and 5 vs. 23 months, P = 0.015, respectively), and this was most pronounced in FLT3-ITD-positive/NPM1-positive patients. We observed altered in vitro sensitivity to topoisomerase inhibitory drugs, but not to nucleoside analogues, and a decrease in global DNA methylation in cells carrying both CDA variant alleles. A shorter survival was also observed for the cN-II variant allele, but only in FLT3-ITD-negative patients (25 vs. 31 months, P = 0.075). Our results indicate that polymorphisms in genes related to nucleoside analog drug metabolism may serve as prognostic markers in de novo NK-AML.

BAALC overexpression retains its negative prognostic role across all cytogenetic risk groups in acute myeloid leukemia patients

Overexpression of brain and acute leukemia cytoplasmic (BAALC) gene confers poor prognosis in cytogenetically normal acute myeloid leukemia (AML) patients, while less defined is its role in AML with abnormal karyotype. We evaluated the effect of BAALC overexpression on outcome of 175 adult AML patients with different cytogenetic risks. Karyotype was favorable in 13, intermediate in 117 and unfavorable in 45 patients, respectively. Quantitative BAALC expression was determined by real-time PCR, with cut off value set at 50th percentile. BAALC was overexpressed in 87/175 (50%) patients, without association with cytogenetic status. High BAALC was associated with unmutated NPM (P = 0.006) and CD34 positivity (P < 0.0001). Complete remission (CR) was attained in 111 patients (63%), and was maintained at 5 years in 52 ± 7%. BAALC overexpression had a negative impact on CR achievement (P = 0.04), while did not influence relapse probability. Median survival was 22 months with a 5-years overall survival (OS) of 35%. Factors with a negative impact on OS were older age (P = 0.0001), unfavorable cytogenetic (P = 0.005), ABCG2 overexpression (P = 0.03) and high BAALC levels (P = 0.01). We observed a worse outcome in patients with high BAALC expression through all cytogenetic risk categories: 5-years OS was 100% vs. 71% in patients with favorable cytogenetics (P = 0.05), 55% vs. 40% in cases with intermediate karyotype (P = 0.04) and 34% vs. 23% in unfavorable cytogenetic subgroup (P = 0.02). BAALC overexpression identified AML patients with poor prognosis in all cytogenetic groups. Though relatively rare, BAALC positivity in patients with favorable or unfavorable karyotype significantly worsened survival.

NUP98-NSD1 fusion in association with FLT3-ITD mutation identifies a prognostically relevant subgroup of pediatric acute myeloid leukemia patients suitable for monitoring by real time quantitative PCR

The cytogenetically cryptic t(5;11)(q35;p15) leading to the NUP98-NSD1 fusion is a rare but recurrent gene rearrangement recently reported to identify a group of young AML patients with poor prognosis. We used reverse transcription polymerase chain reaction (PCR) to screen retrospectively diagnostic samples from 54 unselected pediatric AML patients and designed a real time quantitative PCR assay to track individual patient response to treatment. Four positive cases (7%) were identified; three arising de novo and one therapy related AML. All had intermediate risk cytogenetic markers and a concurrent FLT3-ITD but lacked NPM1 and CEBPA mutations. The patients had a poor response to therapy and all proceeded to hematopoietic stem cell transplant. These data lend support to the adoption of screening for NUP98-NSD1 in pediatric AML without otherwise favorable genetic markers. The role of quantitative PCR is also highlighted as a potential tool for managing NUP98-NSD1 positive patients post-treatment.

The evolving landscape in the therapy of acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous clonal disorder of myeloid precursors arrested in their maturation, creating a diverse disease entity with a wide range of responses to historically standard treatment approaches. While significant progress has been made in characterizing and individualizing the disease at diagnosis to optimally inform those affected, progress in treatment to reduce relapse and induce remission has been limited thus far. In addition to a brief summary of the factors that shape prognostication at diagnosis, this review attempts to expand on the current therapies under investigation that have shown promise in treating AML, including hypomethylating agents, gemtuzumab ozogamicin, FLT3 tyrosine kinase inhibitors, antisense oligonucleotides, and other novel therapies, including aurora kinases, mTOR and PI3 kinase inhibitors, PIM kinase inhibitors, HDAC inhibitors, and IDH targeted therapies. With these, and undoubtedly many others in the future, it is the hope that by combining more accurate prognostication with more effective therapies, patients will begin to have a different, and more complete, outlook on their disease that allows for safer and more successful treatment strategies.

WT1 mutation in pediatric patients with acute myeloid leukemia: a report from the Japanese Childhood AML Cooperative Study Group

Mutations in Wilms tumor 1 (WT1) have been reported in 10-22 % of patients with cytogenetically normal acute myeloid leukemia (CN-AML), but the prognostic implications of these abnormalities have not been clarified in either adults or children. One hundred and fifty-seven pediatric AML patients were analyzed for WT1 mutations around hotspots at exons 7 and 9; however, amplification of the WT1 gene by the reverse transcriptase-polymerase chain reaction was not completed in four cases (2.5 %). Of the 153 evaluable patients, 10 patients (6.5 %) had a mutation in WT1. The incidence of WT1 mutations was significantly higher in CN-AML than in others (15.2 vs. 4.5 %, respectively, P = 0.03). Of the 10 WT1-mutated cases, eight (80 %) had mutations in other genes, including FLT3-ITD in two cases, FLT3-D835 mutation in two, KIT mutation in three, MLL-PTD in three, NRAS mutation in one, and KRAS mutation in two (in some cases, more than one additional gene was mutated). The incidences of KIT and FLT3-D835 mutations were significantly higher in patients with than in those without WT1 mutation. No significant differences were observed in the 3-year overall survival and disease-free survival; however, the presence of WT1 mutation was related to a poor prognosis in patients with CN-AML, excluding those with FLT3-ITD and those younger than 3 years.

Mitochondrial cytochrome c oxidase subunit II variations predict adverse prognosis in cytogenetically normal acute myeloid leukaemia

Alterations in the two catalytic genes cytochrome c oxidase subunits I and II (COI and COII) have recently been suggested to have an adverse impact on prognosis in patients with acute myeloid leukaemia (AML). In order to explore this in further detail, we sequenced these two mitochondrial genes in diagnostic bone marrow or blood samples in 235 patients with AML. In 37 (16%) patients, a non-synonymous variation in either COI or COII could be demonstrated. No patients harboured both COI and COII non-synonymous variations. Twenty-four (10%) patients had non-synonymous variations in COI, whereas 13 (6%) patients had non-synonymous variations in COII. The COI and COII are essential subunits of cytochrome c oxidase that is the terminal enzyme in the oxidative phosphorylation complexes. In terms of disease course, we observed that in patients with a normal cytogenetic analysis at disease presentation (CN-AML) treated with curative intent, the presence of a non-synonymous variation in the COII was an adverse prognostic marker for both overall survival and disease-free survival (DFS) in both univariate (DFS; hazard ratio (HR) 4.4, P = 0.006) and multivariate analyses (DFS; HR 7.2, P = 0.001). This is the first demonstration of a mitochondrial aberration playing an adverse prognostic role in adult AML, and we argue that its role as a potentially novel adverse prognostic marker in the subset of CN-AML should be explored further.

Overexpression of primary microRNA 221/222 in acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is a hematopoietic malignancy with a dismal outcome in the majority of cases. A detailed understanding of the genetic alterations and gene expression changes that contribute to its pathogenesis is important to improve prognostication, disease monitoring, and therapy. In this context, leukemia-associated misexpression of microRNAs (miRNAs) has been studied, but no coherent picture has emerged yet, thus warranting further investigations.

Methods

The expression of 636 human miRNAs was compared between samples from 52 patients with AML and 13 healthy individuals by highly specific locked nucleic acid (LNA) based microarray technology. The levels of individual mature miRNAs and of primary miRNAs (pri-miRs) were determined by quantitative reverse transcriptase (qRT) PCR. Transfections and infections of human cell lines were performed using standard procedures.

Results

64 miRNAs were significantly differentially expressed between AML and controls. Further studies on the clustered miRNAs 221 and 222, already known to act as oncogenes in other tumor types, revealed a deficiency of human myeloid cell lines to process vector derived precursor transcripts. Moreover, endogenous pri-miR-221/222 was overexpressed to a substantially higher extent than its mature products in most primary AML samples, indicating that its transcription was enhanced, but processing was rate limiting, in these cells. Comparison of samples from the times of diagnosis, remission, and relapse of AML demonstrated that pri-miR-221/222 levels faithfully reflected the stage of disease.

Conclusions

Expression of some miRNAs is strongly regulated at the posttranscriptional level in AML. Pri-miR-221/222 represents a novel molecular marker and putative oncogene in this disease.

Integrating post induction WT1 quantification and flow-cytometry results improves minimal residual disease stratification in acute myeloid leukemia

Fifty uniformly treated adult AML patients were analyzed with respect to pre-treatment and post-induction risk factors. Forty-two patients achieving complete hematological remission were assessed for minimal residual disease (MRD) by WT1 gene expression; 34 by flow-cytometry (flow-MRD). Patients who were flow-MRD negative had a better 3-year disease-free (DFS; 79.5% vs. 27.3%; p=.032) compared with patients who were still positive after induction. Interestingly, DFS of flow-MRD positive patients was not related to the amount of flow-detected clone population (≥ or <1%, p=.41) but to WT1 reduction (ΔWT1, 3-year DFS; 46.2% vs. 0% if ΔWT1 was ≥ or < of 1.5 log, p=.001). In AML, combining MRD results provided by WT1 quantification and flow-cytometry improves the reliability of MRD-based prognostic stratification. Similar analyses by further larger studies should be advocated.

Functional regulation of the apurinic/apyrimidinic endonuclease 1 by nucleophosmin: impact on tumor biology

Nucleophosmin 1 (NPM1) is a nucleolar protein involved in ribosome biogenesis, stress responses and maintaining genome stability. One-third of acute myeloid leukemias (AMLs) are associated with aberrant localization of NPM1 to the cytoplasm (NPM1c+). This mutation is critical during leukemogenesis and constitutes a good prognostic factor for chemotherapy. At present, there is no clear molecular basis for the role of NPM1 in DNA repair and the tumorigenic process. We found that the nuclear apurinic/apyrimidinic endonuclease 1 (APE1), a core enzyme in base excision DNA repair (BER) of DNA lesions, specifically interacts with NPM1 within nucleoli and the nucleoplasm. Cytoplasmic accumulation of APE1 is associated with cancers including, as we show, NPM1c+ AML. Here we show that NPM1 stimulates APE1 BER activity in cells. We provide evidence that expression of the NPM1c+ variant causes cytoplasmic accumulation of APE1 in: (i) a heterologous cell system (HeLa cells); (ii) the myeloid cell line OCI/AML3 stably expressing NPM1c+; and (iii) primary lymphoblasts of NPM1c+ AML patients. Consistent with impaired APE1 localization, OCI/AML3 cells and blasts of AML patients have impaired BER activity. Cytoplasmic APE1 in NPM1c+ myeloid cells is truncated due to proteolysis. Thus, the good prognostic response of NPM1c+ AML to chemotherapy may result from the cytoplasmic relocalization of APE1 and the consequent BER deficiency. NPM1 thus has an indirect but significant role in BER in vivo that may also be important for NPM1c+ tumorigenesis.

BAALC and WT1 expressions from diagnosis to hematopoietic stem cell transplantation: consecutive monitoring in adult patients with core-binding-factor-positive AML

No consecutive analysis of BAALC and WT1 expressions associated with core-binding factor AML (CBF-AML) from diagnosis to hematopoietic stem cell transplantation (HSCT) has yet been reported. We investigated BAALC and WT1 expressions using a method of real-time quantitative polymerase chain reaction (RQ-PCR) at diagnosis, after induction chemotherapy, at pre-HSCT, and at post-HSCT period in 45 consecutive patients [t(8,21) (n = 28), inv(16) (n = 17)], who received HSCT as a post-remission treatment. BAALC and WT1 RQ-PCR decrement ratio (DR) was also calculated at post-induction chemotherapy, at pre-HSCT, and at post-HSCT compared with the diagnostic level. Higher BAALC expression at diagnosis showed significantly inferior OS (P = 0.031), EFS (P = 0.011), and higher CIR (P = 0.002) rates. At post-HSCT, both higher BAALC and WT1 expressions showed significantly inferior OS (P = 0.005, 0.016), EFS (P = 0.002, 0.006), and higher CIR (P = 0.001, 0.003) rates. A subgroup of t(8;21) showing higher BAALC and WT1 expressions at post-HSCT were also associated with inferior OS (P = 0.018, 0.015) and higher CIR rates (P = 0.019, 0.011). While BAALC DR showed no significant results on outcomes, WT1 DR more than 2-log at post-HSCT showed significantly lower CIR rate (P = 0.028). This study showed that higher post-HSCT BAALC and WT1 expressions in patients with CBF-AML may be good markers of minimal residual disease for the prediction of survival and relapse after HSCT.

Serial measurement of WT1 expression and decrement ratio until hematopoietic cell transplantation as a marker of residual disease in patients with cytogenetically normal acute myelogenous leukemia

Using real-time quantitative PCR, we monitored Wilms tumor gene 1 (WT1) expression from diagnosis to hematopoietic stem cell transplantation (HSCT) in adult patients with cytogenetically normal acute myelogenous leukemia (CN-AML) and FLT3-ITD and NPM1 mutations. The values at diagnosis were evaluated in 104 patients. Data collected after induction chemotherapy were available for all patients, but only 68 patients were treated with HSCT. Significant WT1 expression cut-offs were determined by receiver operation characteristic curve analysis, and rates of overall survival (OS) and disease-free survival (DFS) were estimated. WT1 decrement ratios (DR) at postinduction chemotherapy and at pre- and post-HSCT compared with the diagnostic level were calculated. Higher WT1 expression at diagnosis, postinduction chemotherapy, and pre-HSCT showed inferior OS (P = .015, <.001, and .002) and DFS (P = .006, <.001, and .003). The cut-offs were determined at the median for diagnostic WT1 expression and at the 25% level from the top for other time points excluding post-HSCT. The WT1 DR ≥ 1-log after induction chemotherapy showed superior OS and DFS (P = .009 and .002) and WT1 DR ≥ 1-log preceding HSCT also showed superior OS and DFS (P = .009 and .003). Results of WT1 DR were consistently applicable in each subgroup with higher (≥ 1.0) and lower (<1.0) WT1 expression at diagnosis and also in NPM1-wild-type/FLT3-ITD-negative CN-AML. The WT1 DR therefore predicted survival outcomes after HSCT more accurately than did the diagnostic WT1 expression. WT1 expression may serve as a reliable marker for residual disease and WT1 DR as a prognostic indicator, particularly in NPM1-wild-type/FLT3-ITD-negative CN-AML. These measures may be applied throughout the course of treatment and even after HSCT.

Characterization of chromosome 11 breakpoints and the areas of deletion and amplification in patients with newly diagnosed acute myeloid leukemia

Chromosome 11 abnormalities are found in many hematological malignancies. In acute myeloid leukemia (AML), a proto-oncogene MLL (11q23.3) is frequently altered. However, rearrangements involving other regions of chromosome 11 have been reported. Therefore, we have characterized the chromosome 11 breakpoints and common deleted and amplified areas in the bone marrow or peripheral blood cells of newly diagnosed patients with AML. Using molecular-cytogenetic methods (multicolor fluorescence in situ hybridization (mFISH), multicolor banding (mBAND), microarrays, and FISH with bacterial artificial chromosome (BAC) probes, chromosome 11 abnormalities were delineated in 54 out of 300 (18%) newly diagnosed AML patients. At least 36 different chromosome 11 breakpoints were identified; two were recurrent (11p15.4 in the NUP98 gene and 11q23.3 in the MLL gene), and three were possibly nonrandom: 11p13 (ch11:29.31-31.80 Mb), 11p12 (ch11:36.75-37.49 Mb) and 11q13.2 (68.31-68.52 Mb). One new MLL gene rearrangement is also described. No commonly deleted region of chromosome 11 was identified. However, some regions were affected more often: 11pter-11p15.5 (n = 4; ch11:0-3.52 Mb), 11p14.1-11p13 (n = 4; ch11:28.00-31.00 Mb) and 11p13 (n = 4; ch11:31.00-31.50 Mb). One commonly duplicated (3 copies) region was identified in chromosomal band 11q23.3-11q24 (n = 9; ch11:118.35-125.00 Mb). In all eight cases of 11q amplification (>3 copies), only the 5' part of the MLL gene was affected. This study highlights several chromosome 11 loci that might be important for the leukemogeneic process in AML.

Genetic risk prediction for normal-karyotype acute myeloid leukemia using whole-exome sequencing

Normal-karyotype acute myeloid leukemia (NK-AML) is a highly malignant and cytogenetically heterogeneous hematologic cancer. We searched for somatic mutations from 10 pairs of tumor and normal cells by using a highly efficient and reliable analysis workflow for whole-exome sequencing data and performed association tests between the NK-AML and somatic mutations. We identified 21 nonsynonymous single nucleotide variants (SNVs) located in a coding region of 18 genes. Among them, the SNVs of three leukemia-related genes (MUC4, CNTNAP2, and GNAS) reported in previous studies were replicated in this study. We conducted stepwise genetic risk score (GRS) models composed of the NK-AML susceptible variants and evaluated the prediction accuracy of each GRS model by computing the area under the receiver operating characteristic curve (AUC). The GRS model that was composed of five SNVs (rs75156964, rs56213454, rs6604516, rs10888338, and rs2443878) showed 100% prediction accuracy, and the combined effect of the three reported genes was validated in the current study (AUC, 0.98; 95% confidence interval, 0.92 to 1.00). Further study with large sample sizes is warranted to validate the combined effect of these somatic point mutations, and the discovery of novel markers may provide an opportunity to develop novel diagnostic and therapeutic targets for NK-AML.

Development of gene expression-based risk score in cytogenetically normal acute myeloid leukemia patients

Patients with normal karyotype represent the single largest cytogenetic group of acute myeloid leukemia (AML), with highly heterogeneous clinical and molecular characteristics. In this study, we sought to determine new prognostic biomarkers in cytogenetically normal (CN)-AML patients. A gene expression (GE)-based risk score was built, summing up the prognostic value of 22 genes whose expression is associated with a bad prognosis in a training cohort of 163 patients. GE-based risk score allowed identifying a high-risk group of patients (53.4%) in two independent cohorts of CN-AML patients. GE-based risk score and EVI1 gene expression remained independent prognostic factors using multivariate Cox analyses. Combining GE-based risk score with EVI1 gene expression allowed the identification of three clinically different groups of patients in two independent cohorts of CN-AML patients. Thus, GE-based risk score is powerful to predict clinical outcome for CN-AML patients and may provide potential therapeutic advances.

The effect of aqueous cinnamon extract on the apoptotic process in acute myeloid leukemia HL-60 cells

BACKGROUND

Acute promyelocytic leukemia (APL) is an acute leukemia diagnosed by translocation of chromosomes 15 and 17 [T (15,17)] and aggregation of neoplastic promyelocytes which are incapable of being converted into mature cells. Today, many tend to use medicinal herbs in studies and clinical applications for treatment of cancers. Cinnamon with scientific name "cinnamomumzelanicum" is a shrub of Laurales order, lauraceae family with cinnamomum genus. It is a medicinal shrub with anti-proliferation effect on tumor cells. This study was conducted to determine the effects of aqueous cinnamon extract on HL-60 cells as a model for APL.

MATERIALS AND METHODS

In this in vitro experimental study, HL-60 cell line was cultured under the influence of cinnamon extract's concentrations of 0.01, 0.1, 1, and 2 mg/ml in with intervals of 24, 48, and 72 h. Growth inhibition and toxic effects of cinnamon extract were evaluated through tetrazolium salt reduction. The effect of this herb on the cell cycle was studied by flow cytometry. The Hoechst stain was used to detect apoptotic cell nuclei.

RESULTS

Cinnamon extract inhibited the growth of HL-60 cells as correlated with concentration and time. After 72 h of treating HL-60 cells with 0.01 mg/l cinnamon extract, the growth of cells was inhibited by 90.1%. Cinnamon extract stopped the cell cycle in G1 phase and the Hoechst staining verified the apoptotic process in those cells.

CONCLUSION

Considering the inhibitory property of cinnamon extract, we recommend it as a single drug or besides other medications for treating promyelocytic leukemia.

Curability of patients with acute myeloid leukemia who did not undergo transplantation in first remission

PURPOSE

The aims of this study were to quantify the prospects of salvage treatment of patients who did not undergo transplantation in first complete remission (CR1) and to assess the contribution of allograft in second complete remission (CR2) with respect to major risk groups. This evaluation can inform the decision whether to offer a transplant in CR1.

PATIENTS AND METHODS

Of 8,909 patients who entered the Medical Research Council AML10, AML12, and AML15 trials, 1,271 of 3,919 patients age 16 to 49 years who did not receive a transplant in CR1 relapsed. Of these patients, 19% are alive beyond 5 years compared with 7% of patients who relapsed after an allograft in CR1. Overall survival and the contribution of a transplant in CR2 were assessed overall and by cytogenetic risk group by using Mantel-Byar analysis.

RESULTS

Fifty-five percent of patients who relapsed entered CR2. This percentage varied by risk group as follows: favorable (82%), intermediate (54%), adverse (27%), and unknown (53%), which resulted in 5-year survivals of 32%, 17%, 7%, and 23%, respectively. Sixty-seven percent of remitters received an allotransplant that delivered superior survival compared with patients who did not receive a stem-cell transplant (42% v 16%). A more-stringent assessment of a transplant by using delayed-entry (Mantel-Byar) analysis confirmed the benefit of transplant overall and within intermediate and adverse risk groups but not the favorable subgroup.

CONCLUSION

Successful salvage treatment of patients who do not undergo transplantation in CR1 and relapse can be achieved in 19% of patients, which is improved by a transplant except in favorable risk disease. This result suggests that, for intermediate-risk patients in particular, equivalent overall survival can be achieved by delaying transplantation until after relapse, which would require many fewer transplants.